


there's nothing in this world i wouldn't do

by 3rdgymbros



Category: Haikyuu!!
Genre: Aobajousai, Brother-Sister Relationships, Gen, Manager reader
Language: English
Status: Completed
Published: 2020-07-26
Updated: 2020-07-26
Packaged: 2021-03-06 01:33:59
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 4
Words: 1,557
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25525231
Author URL: https://archiveofourown.org/users/3rdgymbros/pseuds/3rdgymbros
Summary: in which the reader is oikawa's little sister, and serves as seijoh's unofficial manager.
Relationships: Oikawa Tooru/Reader
Kudos: 45





	1. childhood one.

**Author's Note:**

> Please leave a review!

“Tooru?”

His sister peeks out into the waiting room, her face flushed. Her brown hair sticks up in sweaty spikes, and a fine sheen of sweat glistens on her forehead, but her smile and eyes are both bright.

Perched on the hard plastic chair, Oikawa Tooru looks at Oikawa Tamiko and immediately asks, “Has the screaming stopped?”

“You have to see her, Tooru, she’s so gorgeous!” His sister cries, barreling into him and practically yanking him to his feet. “It was incredible!”

Their definition of incredible must be light years apart, Tooru thinks, trailing behind Tamiko and into the hospital room.Dad bustles about, arranging flowers and gifts on the table while Mom lounges on the bed. Tentative steps takeTooru to the edge, and he gasps in horror. His sister is _not_ an attractive baby. Red legs and arms, hands splayed, an open mouth, and the most hideous dark hair on her ears. Mom, though visibly tired, is all smiles as she waveshim over to hold his “new best friend”.

So Tooru settles in beside her, pillows fluffing behind him, and she places the wiggly bundle in his arms. His sister’s eyes are half-open; her nose is a smudge.Rosy lips pucker and tiny fists wave.

And _that’s_ when he falls in love with her. That’s when Tooru knows that he’ll fight and fight for this child, no matter what. That he’s going to protect his sister no matter what.

“What should we name her?” Mom asks fondly, looking down at him with a soft smile.

When short, chubby fingers wrap around one of his, skin soft and warm,Tooru decides that hair on the ears isn’t such a terrible thing, after all. “ **(Y/n)** ,”He replies immediately. “We should name her **(Y/n)**.”

The bundle in his arms gurgles, and Tooru takes that as approval. So does Mom, whose soft chuckle washes over him.

“I like that,” She says. “Welcome to the family, **(Y/n)**.”


	2. childhood two.

**Notes for the Chapter:**

> Please leave a review!

It’s raining outside when they bring **(Y/n)** home, but her new room is full of sunshine. The cream colored walls, the new bright yellow curtains with their crisp white ribbon trim. The soft rug, the cuddly bears, the changing table and the honey-colored cot with its light blue blankets and its mobile of sheep and clouds.

 **(Y/n)** ’s dressed in a green sleep suit and white socks, her eyes closed and her hands balled up in tiny fists near her face. Her eyes are wrinkled, her eyebrows little pencil sketches in her face. As Tooru watches, standing on his tip toes to peer into the cot, the baby heaves in a deep breath and then lets it out.

“ **(Y/n)** ,” He whispers, unable to tear his eyes away, “ **(Y/n)** , it’s me. My name’s Tooru, and I’m your older brother.”

There’s a snuffle, and a hiccup, impossibly high-pitched and small. And then a happy gurgle, as if she’s heard him, and **(Y/n)** opens big, bright eyes, which fall onto Tooru, and her chubby cheeks lift in a smile.

 _“Oh,”_ Tooru says, unable to say much else. He strokes a finger down **(Y/n)** ’s cheek, and, still smiling, the baby instinctively turns her head to it. Tooru can feel the softness, the silken downy hair.

“Hello, **(Y/n)** ,” Tooru whispers. It’s by far the loudest sound in the room. “I’m your brother.”

 **(Y/n)** gazes up into his face, trusting and sweet.

Tooru stares back, wrapped in his world of two.


	3. childhood three.

**Notes for the Chapter:**

> Please leave a review!

Through the door, he can hear **(Y/n)** wailing.

He has a key; Tooru opens the door and slips inside. The living room looks as if a bomb’s exploded in in. Every light is on and the television is playing canned music. Among the wreckage, mum strides with **(Y/n)** on her shoulder, patting the baby’s back and gently bouncing her little body. Keeps walking in circles around the perimeter of the room, kept bouncing, skirting nappies and cuddly animals.

“Tooru, welcome home,” Mum says, and her lined face creases into a tired smile. “There’s tofu soup and rice for lunch.”

His sister’s face is red, screwed up into a tight little ball of anger with an open toothless mouth.

“I’m home,” Tooru says slowly, dumping his bag on the floor; normally, mum would tell him to pick it up, but she’s preoccupied with her youngest child, and temporarily lets him off the hook. “Is she sick?”

“ **(Y/n)** ’s fine, just _fussy_. She started crying an hour ago and she just hasn’t stopped. Nothing works.”

“Is she in pain?”

A feeling of anguish and upset bubbles up in his chest; Tooru can’t remember the last time he’s felt so wretched, except for that time a month ago when Iwa-chan had fought with him, and they hadn’t spoken for a week. Every cry wrenches his insides, calls on all his instincts to soothe and protect.

“Let’s wait a little while and see if she settles down. I’ll heat up the milk . . . Could you please watch **(Y/n)** for a second?” She bends to give him a kiss on the cheek, and just as quickly as she kisses him, the baby is deposited in his arms.

The baby pauses for a moment, sensing the change in minders, and then begins crying again. His mother flits into the kitchen, and Tooru is left to sit on the sofa, feeling a bit helpless, and definitely out of his depth.

His body adjusts to hold the tiny bundle by itself. Her legs are curled up like the tops of musical notes, and her body is more solid and heavy than he’d expected. **(Y/n)** fits in his arms as if she’s always meant to be there. Her hair whorls around her forehead, and his full, rosebud lips pucker out.

“It’s okay,” He mumbles, patting her on her soft crown, her back, anywhere really, in the hopes that she’ll stop crying. “It’s okay, don’t cry, everything’s fine.”

The volume of the baby’s cries suddenly rises up into a scream, and then subsides into a whimper. And then silence.

Alarmed, Tooru bends towards **(Y/n)**. Her cheeks are pink, not red, and she gazes calmly back at him with big, bright eyes, as if wondering why he’s making such a fuss.

“Would you look at that,” From the kitchen, his mother’s voice floats into earshot, “I guess she just wanted her brother.”


	4. teenage years one.

**Notes for the Chapter:**

> Please leave a review!

The TV projects a movie into the dark living room, throwing pinpricks of light onto Tooru’s face. Tonight is movie night, and it’s Tooru’s turn to choose – he’s picked _Alien_. He fields a strange obsession for the space and the unknown, but you can’t really criticize him for it, since you’re currently going through a Disney phase.

Swaddled in a metric ton of blankets, you cuddle closer to him. Tooru snakes a strong arm around your ribs. “How was school today?”

"The usual."

Stubbornly, you refuse to elaborate further. You aren't a social butterfly like your brother is, and it's glaringly apparent in the way that you make no efforts to seek out friends. Your school life is just that; _school_ , with you running over to the Seijoh gymnasium once school lets out, to assist with your brother's volleyball team as the unofficial manager. Not once have you stopped off at convenience stores with friends your own age, not once have you ever been asked out. You keep your classmates at arms' length, and that's fine.

Tooru purses his lips, but doesn't reply. He's told you a few times that you should be making an effort to get along with your classmates, but it's nothing that you haven't heard before, nothing that isn't easily tuned out.

"How was practice?" he asks instead, and you breathe a silent sigh, thankful for the change in subject.

"You were there, weren't you?" Your retort is razor-sharp, but you wince almost instantly, remembering his doctor's appointments and the old injury plaguing him. " – Oh, yeah, right, no. Sorry. Everyone's really working hard. Iwa-chan kept the team in shape while you were gone."

Tooru lets out a non-committed hum, but you know your brother like you know your own mind; these constant days of going without practice have him worried, and the moment the doctor gives him the okay tomorrow, he'll be back on the court, practicing without so much as taking a break to breathe.

"You arranged for a practice match with Karasuno tomorrow, yeah?" You crinkle your nose at the blood splashing across the screen, the infamous chest-burster scene playing out in full definition glory on the wide screen tv. "Don't you have a last checkup tomorrow? Will you make it on time?"

"I will." A savage light makes itself known in his eyes then. "I'm looking forward to seeing my cute little Tobio-chan, and crushing him once and for all."

You deliver a well-timed poke to his ribs, the spot where he's most ticklish, and take a savage delight in hearing his indignant squawk. "Would it kill you to be nice to him? It's just a practice match."

"D'you still have that crush on him?"

Now, it's your turn to squawk. "Crush?! It wasn't a crush, we just – We weren't even friends, not really, we just spoke once or twice –"

Oikawa cackles, sounding high and deranged. "You're rambling, you totally liked him –"

"Shut up!"


End file.
